Question

GMC Envoy XL problem with the A/C and heater fan not coming on, at all. Therefore, no heat and no cooling. Need help.

My 2003 Envoy XL's problem is with the A/C & Heater fan not coming on, at all. No heat and no cooling. Anyone have an idea what the cause might be?

I've checked the fuses and relays and they seem to be ok. I don't know where the fan is located, I guess behind the dash. I assume the A/C and Heater are ok since the fan will not work when I have either on. The fan will not work with the A/C off and vent on. Can anyone help me figure this out?

On the outside a relay will not always change in apperance if it is working or not... How do you know the relay is good? Did you switch it with another relay and it operated the component it was intended to work for. Example; if you trade places of the horn relay and the blower motor relay, you say the blower motor relay is good, so when you trade them out it the horn should work with the same relay that you had in the blower motor spot. And vise versa. Or you tested it with a 9v battery and you can hear and feel the relay switching inside... If its not the relay then I check for voltage at the blower motor plug in, if there is 12volts there Id replace the blower motor. Dont forget to have the key on and the blower switch on high when checking for voltage at the plug in...

Ok with the volt meter on DC setting, put the black lead to a known good ground such as the door hinge or hinge bolt, make sure you scrape down past the paint for a good connection. Then with the car RUNNING and the blower switch on HIGH stick the red lead of the meter to each wire and one of them should have voltage somewhere in the neighborhood of 12 volts, if everything is kosher.... If you get voltage then you have to replace the blower motor...If you dont let me know...

On the outside a relay will not always change in apperance if it is working or not... How do you know the relay is good? Did you switch it with another relay and it operated the component it was intended to work for. Example; if you trade places of the horn relay and the blower motor relay, you say the blower motor relay is good, so when you trade them out it the horn should work with the same relay that you had in the blower motor spot. And vise versa. Or you tested it with a 9v battery and you can hear and feel the relay switching inside... If its not the relay then I check for voltage at the blower motor plug in, if there is 12volts there Id replace the blower motor. Dont forget to have the key on and the blower switch on high when checking for voltage at the plug in...

Ok with the volt meter on DC setting, put the black lead to a known good ground such as the door hinge or hinge bolt, make sure you scrape down past the paint for a good connection. Then with the car RUNNING and the blower switch on HIGH stick the red lead of the meter to each wire and one of them should have voltage somewhere in the neighborhood of 12 volts, if everything is kosher.... If you get voltage then you have to replace the blower motor...If you dont let me know...